package lab02.test36;

public class Undergraduate extends Student {
    @Override
    String calGrade() {
        double avg=average();
        if (avg>=80&&avg<=100)
            grade="优秀";
        else if (avg>=70&&avg<70)
            grade="良好";
        else if (avg>=50&&avg<60)
            grade="及格";
        else
            grade="不及格";
        return null;
    }
}
